1. Field
The presently disclosed subject matter relates to semiconductor light-emitting devices in which light emitted from a semiconductor light-emitting chip is wavelength-converted by a wavelength converting layer, and to manufacturing methods for the same. More particularly, the disclosed subject matter relates to semiconductor light-emitting devices for a vehicle light and the like, which can form a desired light distribution pattern including a light-emitting line such as a horizontal cut-off line with high light-efficiency, and to methods of manufacturing such devices.
2. Description of the Related Art
Semiconductor light sources, in which a part of the light emitted from a semiconductor light-emitting chip is converted into light having a different wavelength by a phosphor and in which a mixture light including the light having the different wavelength mixed with the light emitted directly from the light-emitting chip is emitted, have been used as a light source for various lighting units. In this case, LED light sources that emit light having a desired light distribution pattern by covering a surrounding area of a light-emitting surface thereof with a light-shielding member have been known.
Conventional LED light sources including a light-shielding layer are disclosed in Patent Document No. 1 (U.S. Pat. No. 7,679,100) and Patent Document No. 2 (Japanese Patent Application Laid Open JP2007-103937), which is a Japanese patent application corresponding to Patent Document No. 1. FIGS. 11a and 11b are respectively a schematic top view and a schematic side cross-section view showing a first conventional LED light source, which may be used as a light source for a vehicle headlight and which is disclosed in Patent Documents No. 1 and No. 2.
The first conventional LED light source 30 includes: a casing 32 having a cavity 31 composed of a base board 32a and a frame 32b, and the cavity 31 being formed in the casing 32, which is structured by the base board 32a and the frame 32b; a plurality of LED chips 34 located on the base board 32a in the cavity 31 so as to be spaced at a predetermined interval from a wall 35 of the frame 32b of the casing 32; external electrodes 37 being electrically connected to each of the electrodes of the LED chips 34 via bonding wires 36 for receiving a power supply from an outside battery; and an encapsulating resin 39 disposed in the cavity 31 to encapsulate the LED chips 34.
A wavelength converting material may be mixed in the encapsulating resin 39 so as to be able to wavelength-convert light emitted from the LED chips 34. The wavelength converting material may also be located on the encapsulating resin. In addition, the first LED light source 30 includes a light-shielding layer 33 on a top surface of the frame 32b so that a side surface of the light-shielding layer 33 is aligned with the wall 35 of the casing 32.
Accordingly, the first LED light source 30 may emit white light having a light distribution pattern, which is similar to an enlarged shape of an opening of the cavity 31 that is a light-emitting surface of the LED light source 30 and which includes a light-emitting line having a high contrast that is formed by the light-shielding layer 33. When the first conventional LED light source 30 is used as a light source for a vehicle headlight, the light-emitting line having a high contrast may be used to form a horizontal cutoff line for a low beam.
FIGS. 12a and 12b are a schematic top view and a schematic side cross-section view showing a second conventional LED light source, which may be used as a light source for a vehicle headlight and which is disclosed in Patent Documents No. 3 (Japanese Patent Application Laid Open JP2009-526377). The second conventional LED light source 40 includes: a casing 42 having a cavity 41 composed of a base board 42a and a frame 42b, and the cavity 41 being formed in the casing 42, which is structured by the base board 42a and the frame 42b; a plurality of LED chips 44 located on the base board 42a in the cavity 41 so as to be spaced at a predetermined interval from a wall 45 of the frame 42b of the casing 42; conductor patterns 47 being electrically connected to each of the electrodes of the LED chips 44 via bonding wires 46 so as to receive a power supply from an outside battery; and an encapsulating resin 49 disposed in the cavity 41 to encapsulate the LED chips 44.
In this case, a light-shielding layer 43 is provided on a top surface of the frame 42b so that a side surface of the light-shielding layer 43 is aligned with the wall 45 of the casing 42 to form a light-emitting line having a high contrast using the light-shielding layer 43 in the second LED light source 40, in common with the first LED light source 30. In addition, the second LED light source 40 includes a projecting portion 42c in the frame 42b of the casing 42 toward the wall 45.
Therefore, the second LED light source 40 may emit white light having a light distribution pattern, which is similar to an enlarged shape of an opening of the cavity 41 that is a light-emitting surface of the LED light source 40 and which includes the light-emitting line having a high contrast that is formed by the light-shielding layer 43. In this case, the white light emitted from the cavity 41 may become a relatively uniform light and may include another light-emitting line having a middle contrast opposite to the light-emitting line having a high contrast, in addition to a small light-emitting pattern emitted from a smaller light-emitting surface than that of the first LED light source 30.
On the other hand, Patent Document No. 4 (Japanese Patent Application Laid Open H11-340515) discloses a third conventional light source used for an LED display and the like, which may emit light having a high contrast using a light-absorbing layer and which may maintain a high reliability even when high amounts of static electricity occurs or is present. FIGS. 13a and 13b are a schematic top view and a schematic front cross-section view showing the third conventional LED light source, which is disclosed in Patent Document No. 4.
The third conventional LED light source 50 includes: a casing 52 having a cavity 51, and the cavity 51 including a bottom surface; conductor patterns 57 being formed on the bottom surface of the cavity 51, and extending toward a bottom surface of the casing 52 for receiving a power supply from an outside voltage source; at least one LED chip 54 located on one of the conductor patterns 57, and each of electrodes of the LED chip 54 electrically connected to each of the conductor patterns 57 via bonding wires 56; an encapsulating resin 59 disposed in the cavity 51 to encapsulate the LED chip 54; and a static electricity shield layer 55 located on a top surface of the casing 52, and being connected to a shield grand electrode 58 formed on the bottom surface of the casing 52 via a through hole 58a. 
Accordingly, even when high static electricity occurs, because the high static electricity may escape via the shield grand electrode 58 from the static electricity shield layer 55, the third LED light source 50 may be protected from the high static electricity. Moreover, a light-absorbing layer 53 is located on the static electricity shield layer 55 along a boundary between an opening of the cavity 51 and the top surface of the casing 52, and therefore may enhance a contrast between a light-emitting surface of the opening of the cavity 51 and a non-light-emitting surface of the light absorbing layer 53. Hence, the third conventional LED light source 50 may be used as a light source for an LED display apparatus, etc.
In addition, a fourth conventional LED light source, which is used as a light source for an LCD backlight unit and the like, is disclosed in Patent Document No. 5 (European Patent Application EP1189291 A2). FIG. 14 is a schematic perspective view showing the fourth conventional LED light source disclosed in Patent Document No. 5.
The fourth conventional LED light source 60 includes: a base board 62; conductor patterns 67a and 67b formed on surfaces of the base board 62, and extending toward a bottom surface of the base board 62 for receiving a power supply from a voltage source; at least one LED chip 64 located on one of the conductor patterns 67a and 67b, and each of the electrodes of the LED chip 64 is electrically connected to a respective portion of the conductor patterns 67a and 67b via bonding wires 66; an encapsulating resin 69 formed in a rectangular parallelepiped shape to encapsulate the LED chip 64; and a light-shielding layer 63 disposed on side surfaces of the encapsulating resin 69 so as not to disperse light emitted from the LED chip 64 in a crosswise direction.
Consequently, the fourth conventional LED light source 60 may emit white light having a light distribution pattern, which is similar to a top surface of the encapsulating resin 69, from a light-emitting surface of the top surface of the encapsulating resin 69. In this case, the light-shielding layer 63 may improve a contrast between the light-emitting surface of the top surface of the encapsulating resin 69 and a non-light-emitting surface of the side surfaces of the encapsulating resin 69.
When a semiconductor light source is used as a light source for a lighting unit such as a vehicle headlight, which may control light emitted from the light source using a reflector and/or a projector lens, a light source having a small light-emitting surface may be desired to efficiently control light emitted from the light source with a small optical structure. However, in structures including the cavities 31 and 51 such as the first and the third conventional LED light sources 30 and 50, a relatively large cavity is required to locate the at least one LED chip. Therefore, it may be difficult for a structure including a cavity to reduce a light-emitting surface, because the opening of the cavity becomes the light-emitting surface.
In a structure including the raised encapsulating resin 69 from the base board 62 such as the fourth conventional light source 60, because a relatively large amount of encapsulating resin is required to encapsulate the at least one LED chip 64, the structure may also result in difficulty in reducing the light-emitting surface of the top surface of the encapsulating resin 69. In a structure including the projecting portion 42c in the frame 42b such as in the second conventional LED light source 40, the structure may allow relatively easy reduction of the light-emitting surface by extending the projecting portion 42c toward the wall 45 of the casing 42. However, a light-emitting efficiency of the light source 40 may decrease because the projecting portion 42 may interrupt a part of light emitted from the LED chips 44.
Hence, inventors of the presently disclosed subject matter disclosed a conventional semiconductor light-emitting device that can be used as a light source for a vehicle headlight and the like in Patent Document No. 6 (U.S. patent application Ser. No. 13/162,152) and Patent Document No. 7 (U.S. patent application Ser. No. 13/196,868), which can emit light having a high light-emitting efficiency from a small light-emitting surface. In these cases, a reflective material layer can be located around the small light-emitting surface, and therefore a contrast between the light-emitting surface and a non-light-emitting surface of the reflective material layer may not be necessarily high to form a horizontal cut-off line for a vehicle headlight.
On the other hand, each of the first to the fourth conventional LED light sources 30, 40, 50 and 60 may emit light having a high contrast between the light-emitting surface and the non-light-emitting surface using the light-shielding layer. However, a side surface of the light-shielding layer is exposed to the light-emitting surface, and therefore may absorb a part of light emitted from the LED chips. Accordingly, an amount of light emitted from the light-emitting surface may be reduced, and thus the above-described structures may be considered to include a structural problem or characteristic in that the light-emitting surface cannot be reduced.
The above-referenced Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.    1. Patent Document No. 1: U.S. Pat. No. 7,679,100    2. Patent Document No. 2: Japanese Patent Application Laid Open JP2007-103937    3. Patent Document No. 3: Japanese Patent Application Laid Open JP2009-526377    4. Patent Document No. 4: Japanese Patent Application Laid Open H11-340515    5. Patent Document No. 5: European Patent Application EP1189291 A2    6. Patent Document No. 6: U.S. patent application Ser. No. 13/162,151    7. Patent Document No. 7: U.S. patent application Ser. No. 13/196,868
The presently disclosed subject matter has been devised to consider the above and other problems, features, and characteristics in the conventional art devices. Embodiments of the disclosed subject matter can include semiconductor light-emitting devices that can emit a wavelength-converted light having a high light-emitting efficiency and a high contrast between a light-emitting surface and a non-light-emitting surface from a small light-emitting surface, and associated manufacturing methods that do not cause and/or are designed to prevent some of the above-described problems, concerns, and characteristics related to a light-shielding layer. The disclosed subject matter can also include a vehicle headlight using the semiconductor light-emitting device that can form a light distribution pattern including a horizontal cut-off line having a high contrast with a simple structure, which is formed by using a light distribution pattern including a light-emitting line having a high contrast emitted from the light-emitting surface of the device.